1. Field of the Invention
The present invention relates to a fuel tank suitable for a fuel cell system for a mobile power source and a cap device for the fuel tank.
2. Discussion of the Related Art
A fuel tank stores a predetermined amount of fuel, and supplies the stored fuel to specific devices or systems. Typically, the fuel tank is composed of a tank body and a lid for sealing a fuel opening through which fuel is injected into the tank body. Additionally, a transfer pipe for transferring fuel to devices or systems is connected to the fuel tank.
The fuel tank may be used in various devices requiring liquid fuel. For example, the fuel tank may be used in vehicles using chemical energy as a power source, or a power generator such as a fuel cell that produces electrical energy from chemical energy of a fuel.
A fuel cell is a device that generates electrical energy through an electrochemical reaction of hydrogen and oxygen. The fuel cell system produces electrical energy by using liquid fuel such as methanol supplied from a fuel tank. The above-mentioned fuel cell system is classified into a fuel cell system for a mobile power source, a fuel cell system for transport, and a fuel cell system for distributed-generation of electricity.
More specifically, the fuel cell system for a mobile power source means a mobile power source, or a fuel cell system used for charging portable telecommunication equipment. A fuel cell of a Polymer Electrolyte Membrane Fuel Cell (PEMFC) and a Direct Methanol Fuel Cell (DMFC) using a high molecular electrolyte film may be used as a fuel cell suitable for a mobile power source.
When a fuel tank used in a fuel cell system for a mobile power source is hand-carried or carried by a car, the fuel tank may sway violently or may be inclined on its side depending on the system mounting or the transport state.
If the fuel tank sways violently or is inclined on its side, the fuel in the fuel tank may not be supplied to the fuel cell smoothly, reducing the output of the fuel cell. Thus, an apparatus which uses the fuel cell system as a power source can not operate as desired.
Further, if the fuel tank sways violently or is inclined on its side, fuel depletion takes place at an anode side of the fuel cell. In this case, a catalyst layer of the anode side may become eroded when the catalyst layer chemically reacts with oxygen from a cathode side. This erosion may damage the stability and shorten the lifespan of the fuel cell.